Tanya Weerakkody, Hanna Sabelström, Shan V. Andrews, Jean Paul Chadarevian, Marcus Y. Chin, David Tatarakis, Nicholas E. Propson, Do Jin Kim, Richard Théolis, Gian Carlo G. Parico, Hiwot Misker, Jennifer E. Kung, Abira Bandyopadhyay, Yaneth Robles Colmenares, Taggra-Nicole Jackson, Ahlam N. Qerqez, Srijana Balasundar, Sonnet S. Davis, Connie Ha, Rajarshi Ghosh, Ritesh Ravi, Anil Rana, Kyla Germain, Arnold Tao, Ken Xiong, Dylan Braun, Karthik Raju, Kang-Chieh Huang, Lihong Zhan, Jing Guo, Hoda Safari Yazd, Lily Sarrafha, Joia Kai Capocchi, Jonathan Hasselmann, Alina L Chadarevian, Christina Tu, Khaled Mansour, Ghazaleh Eskandari‐Sedighi, Niccoló Tesi, Sven J. van der Lee, Marc Hulsman, Georgii Oshegov, Yolande A.L. Pijnenburg, Meredith Calvert, Henne Holstege, Jung H. Suh, Gilbert Di Paolo, Hayk Davtyan, Joseph W. Lewcock, Mathew Blurton‐Jones, Kathryn M. Monroe
The Alzheimer’s disease (AD) genetic landscape identified microglia as a key disease-modifying cell type. Paired immunoglobulin-like type 2 receptor alpha (PILRA) is an immunoreceptor tyrosine–based inhibitory motif domain–containing inhibitory receptor, expressed by myeloid cells such as microglia. The known protective PILRA G78R gene variant reduces AD risk in apolipoprotein E4 ( APOE4 ) carriers and is enriched in a cohort of healthy centenarians. However, mechanisms underlying protective effects in microglia are undefined. Here, we identified biological functions of PILRA in human induced pluripotent stem cell–derived microglia (iMG) and chimeric AD mice. PILRA knockout (KO) in iMG rescued ApoE4-mediated immunometabolic deficits and prevented lipotoxicity through increased lipid storage, improved mitochondrial bioenergetics, and antioxidant activity. PILRA KO also enhanced microglial chemotaxis and attenuated inflammation. With pharmacological inhibitor studies, we showed that peroxisome proliferator–activated receptor and signal transducer and activator of transcription 1/3 mediated PILRA -dependent microglial functions. AD mice transplanted with human PILRA KO microglia exhibited reduced amyloid pathology and rescued synaptic markers. A high-affinity ligand blocking PILRA antibody phenocopied PILRA KO iMG. These findings suggest that PILRA is a pharmacologically tractable therapeutic target for AD.